DURING the 1949 poliomyelitis epidemic in Melbourne, Australia, McCloskey1 became interested in the relationship between poliomyelitis and immunizations. Frequently parents of poliomyelitis patients raised the question of whether an immunization against whooping cough or diphtheria shortly before the onset of poliomyelitis might have brought on the disease.

McCloskey inquired into the history of immunization of 340 poliomyelitis victims. He found 31 children had been immunized within three months of onset. Paralysis was distinctly more frequent in the inoculated than in the uninoculated limbs. On more precise analysis of the time relationship, he found that the interval between the last inoculation and onset of symptoms ranged from 5 to 32 days in all except two of his 31 patients, whose interval was approximately 60 days. From the evidence collected, he concluded that there was a significant relationship in a number of cases between prophylactic injections and the subsequent development of